A more thorough explanation:

A lost-volume seller is a seller of goods who resells the goods to a different buyer after the original buyer has breached a sales contract. The goods sold to the second buyer would have been sold to them even if the original buyer had not breached the contract.

For example, if a car dealer sells a car to a buyer who later breaches the contract, the dealer can resell the car to another buyer who would have bought the same car from the dealer's inventory. In this case, the dealer is a lost-volume seller and is entitled to lost profits as damages from the original buyer's breach.

The Uniform Commercial Code (UCC) § 2-708(2) provides that a lost-volume seller is entitled to lost profits, rather than contract price less market price, as damages from the original buyer's breach.